The invention relates to a medical aid comprising a lancet and to a sensor comprising a test element, the lancet or the test element being at least partially enclosed by a (preferably flexible) packaging.
In clinical diagnostics, examination of blood samples or of interstitial fluid permits early and reliable detection of pathological conditions and also specific and reliable monitoring of physical states. Medical diagnostics always entails obtaining a sample of blood or of interstitial fluid from the individual who is to be examined.
To obtain the sample, the skin of the person to be examined can be punctured, for example at the finger pad or ear lobe, with the aid of a sterile, sharp lancet, in order in this way to obtain a few microliters of blood for the analysis. This method is particularly suitable for sample analysis that is carried out directly after the sample has been obtained.
In the area of home monitoring in particular, in other words where persons without specialist medical training carry out simple analyses of blood or of interstitial fluid themselves, and particularly for diabetics taking blood samples on a regular basis, several times a day, to monitor their blood glucose concentration, lancets and associated devices (puncturing aids) are sold that allow samples to be taken with the least possible discomfort and in a reproducible manner. Such lancets and devices (puncturing aids) are the subject matter of, for example, WO-A 98/48695, U.S. Pat. No. 4,442,836 or U.S. Pat. No. 5,554,166.
Self-monitoring of blood glucose levels is a method of diabetes control that is nowadays applied worldwide. Blood glucose monitors in the prior art comprise an analysis device into which a test element (test strip) is inserted. The test element is brought into contact with a droplet of a sample which has previously been obtained by means of a puncturing aid, for example from the pad of a finger.
The prior art also includes numerous test elements, and sensors comprising such test elements, which can be used to determine the concentration of at least one analyte (for example glucose, lactate or cholesterol) in the liquid sample, particularly in blood or interstitial fluid. These test elements or sensors can be based, for example, on electrochemical measurement methods, such as are described in U.S. Pat. No. 5,286,362, for example. Other test elements and sensors are based, for example, on an optical detection of the at least one analyte. The analyte can thus react in particular with a detection reagent contained on or in the test element, in which case the test element (for example a test area of the test element) changes at least one measurable optical property (e.g. a color, a fluorescence, a reflectivity, or a combination of these properties). The change in this property can be optically detected, in order to determine from this the concentration of the at least one analyte. Illustrative embodiments of test elements or sensors of this kind, designated hereinbelow also as “optical test elements”, are known from CA 2,050,677, for example.
Test elements and sensors are also known that are packaged in such a way that a magazine comprises several such test elements. For example, several test elements or sensors can be received on an analysis tape. Examples of analysis tapes comprising a plurality of test areas are disclosed in EP 0 299 517 B1.
Sensors and test elements are also known which are not designed for single, brief contact with the sample but are instead configured so as to remain in the sample for a longer measurement period, for example for a few hours, days or weeks. An important use of sensors of this kind is in the field of implantable sensors, for example subcutaneous sensors, which can be implanted under a patient's skin (for example in the interstitial fatty tissue). These sensors are generally designed for continuous monitoring of the analyte concentration, or for monitoring of the analyte concentration at short intervals, and are able to exchange data with a measurement device, for example via an electrical connection. Examples of implantable sensors or test elements of this kind, based on an electrochemical measurement principle, are given in EP 0 678 308 B1 or in EP 0 748 183 B1. Both documents describe not only the actual structure of the sensor but also an insertion aid by means of which the sensor can be implanted. After the implantation, the insertion aid can be removed again from the skin area.
The numerous system components (lancet, puncturing aid, test element and analysis device) require a lot of space and involve quite complex handling. Systems have also been developed which have a greater degree of integration and are thus easier to handle and in which, for example, the test elements are stored in the analysis appliance and made available for the measurement. A further step in terms of miniaturization will be achieved, for example, by integrating several functions or function elements within a single analytical aid (disposable). For example, the operating sequence can be greatly simplified by suitable combination of the puncturing procedure and of the detection of the analyte concentration by means of a sensor on a test element.
In the prior art, it is known to provide the lancets of such analytical aids with a capillary structure or to make them part of a capillary structure (for example from WO 2005/104948 A1). There, after the skin has been punctured and the sample emerges, the lancet tip is brought into contact with the sample in order to collect the latter with the capillary.
The lancet tip of lancets used for blood extraction is typically sterilized in advance and kept in a sterile state by a sterile protector (for example in the form of a cap or pocket) before being used for a puncturing procedure, in order to ensure that the lancet tip is not contaminated by its surroundings. Moreover, measures are often taken to ensure that, after the skin has been punctured, the lancet tip is shielded again (if appropriate by means of the same cap or pocket), such that accidental injuries and associated infections caused by blood adhering to the lancet tip are avoided.
In the case of individual lancets, a sterile protector can be produced, for example, by the lancet tip being encapsulated with plastic by injection molding in one operation together with the production of the lancet body. Before use, the user removes this part manually, generally upon insertion into a puncturing aid. In the case of lancets encased in a magazine, similar sterile protection devices are customary, for example devices in which the lancet is pulled to the rear out of a sterile protector, whereupon the sterile protector is conveyed out of the puncturing path by spring force. Relatively complicated mechanisms, in particular springs that are integrated in the equipment, are required for this.
WO 01/66010 circumvents the complicated nature of this mechanism by means of the sterile protector simply being pierced. WO 01/66010 relates to a lancet that comprises a lancet needle with a tip, and a lancet body that completely surrounds the lancet needle at least in the region of the tip. At least in the region of the tip of the lancet needle, the lancet body is made of an elastic material in which the tip of the lancet needle is embedded. Furthermore, a lancet is described which comprises a lancet needle with a tip and a hollow body that surrounds at least the tip of the lancet needle. The lancet needle is movable in the region of its tip in the hollow body, and the hollow body is made at least partially of an elastic material which can be pierced through by the tip of the lancet needle during the puncturing procedure and which, if appropriate, closes again after the tip of the lancet needle is pulled back into the hollow body.
EP 1 360 935 A1 relates to a tape-like package for a large number of medical aids. The aids are accommodated in depressions in a first tape section that are covered by a second tape section.
EP 1 492 457 B1 relates to an automatically opening package for medical aids that comprises the following:                an upper flexible sheet section which has a distal end, a proximal end, a first peripheral edge and a second peripheral edge,        a lower flexible sheet section which has a distal end, a proximal end, a first peripheral edge and a second peripheral edge,        
wherein the upper and lower flexible sheet sections are designed such that they can be detachably sealed together along at least one segment of their first and second peripheral edges, as a result of which a medical device is enclosed within the upper and lower flexible sheet sections. A collar is mounted on the distal end of the upper flexible sheet section and on the distal end of the lower flexible sheet section, said collar being mounted on the distal ends of the lower and upper flexible sheet sections in such a way that a relative movement of the collar and of the proximal ends of the upper and lower flexible sheet sections that decreases a distance between them causes the upper and lower flexible sheet sections to pull apart. In this way, the package is automatically opened and at least one section of the medical device is exposed. One disadvantage of this automatically opening package is that the lancet tip is arranged in the area of the package that is pulled back with the movement of the collar. This creates the risk of the lancet tip hitting one of the flexible sheet sections or the seam between the two flexible sheet sections. It can then pierce one of the flexible sheet sections and, as the package is opened further, can be bent by the pulling apart of the sheet portions. Moreover, the lancet tip may hit a seam whose mechanical action or adhesive can adversely alter the surface properties of the lancet tip. If the lancet tip has a capillary structure, it must be hydrophilic, for example in order to ensure that the blood transport functions. Its hydrophilic nature is threatened by contact between the lancet tip and the seam of the package.